The prevention and control of post-treatment pain is of great importance for the comfort of the patient as well as for the clinician's prestige. In this study, the effect of 940 nm diode laser disinfection on the postoperative pain of retreatment cases was evaluated.

From the fact that microorganisms are the most common factors causing pain, this study aimed to evaluate effect of 940 nm diode laser disinfection performed in addition to conventional irrigation on postoperative pain of retreatment cases. Eighty-four patients with chronic apical periodontitis were treated. Root canal fillings were removed using rotary files. Root canals were irrigated using sodium hypochlorite between instrument changes. Final irrigation was performed using sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA). The cases were randomly allocated into 2 groups: Group 1: Diode laser disinfection group, Group 2: control group. Root canal fillings were applied and crowns were restored. All treatments were completed in a single appointment. Patients were given a pain scale and they were requested to mark the code that reflects their pain intensity during 3 days.

Inclusion Criteria:

• Only asymptomatic single rooted teeth that had an initial root canal filling diagnosed with chronic periodontitis (minimum size 2x2 mm)

Exclusion Criteria:

• teeth with root canal fillings newer than 4 years, overfilled teeth, teeth with intraradicular posts, existence of a sinus tract, consumption of antibiotics within 1 month, consumption of analgesics in last 5 days, systemic disease, pregnancy, history of trauma, traumatic occlusion